Dresden 2006 – wissenschaftliches Programm

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O: Oberflächenphysik

O 27: Scanning probe techniques II

O 27.8: Vortrag

Dienstag, 28. März 2006, 17:30–17:45, WIL B321

Hydrogen-altered Gd(0001) surfaces investigated by dynamic force microscopy — •Rene Schmidt, Alexander Schwarz, and Roland Wiesendanger — Institute of Applied Physics, University of Hamburg, Jungiusstr. 11, D-20355 Hamburg

Adsorbates from residual gases alter the electronic and magnetic properties of rare earth metals. Here, the chemisorption process of hydrogen on Gd(0001) islands epitaxially grown on W(110) is investigated by means of dynamic force microscopy in UHV. Frequency shift vs. bias curves show a potential difference of 0.6 V between clean and H-covered regions on Gd(0001) islands. This originates from a charge transfer between hydrogen and gadolinium, leading to a bias voltage dependent contrast in DFM images, i.e., H-covered gadolinium surface areas appear depressed for negative or elevated for positive bias voltages, respectively. These results are discussed with respect to photoemission and STM studies, which indicate, that adsorbed hydrogen locally destroys the surface state with d_z²-like orbital symmetry and induces a decreasing differential conductivity near the Fermi level at low bias voltages.